In 2013, nearly three million Americans were living with type 1 diabetes, with 85% of these individuals being adults. As coping with diabetes occurs in a social context, romantic partners likely play an important role in diabetes management. However, little is known about how adults cope with type 1 diabetes management throughout adulthood and the role of romantic partners. Collaborative involvement by romantic partners (jointly coping with challenges of diabetes) may facilitate daily diabetes management in the face of competing work and family pressures among young and middle-aged adults and may be especially important for older adults who may be adept at collaboration but experiencing reduced cognitive and physical reserves. The proposed study applies an adult life-span perspective to examine the stressors that are linked to diabetes management during young, middle-aged, and older adulthood and the ways that romantic partners may facilitate diabetes management across time through collaborative coping processes. The study employs a multi-method, multisite, 6-month longitudinal design that will examine collaborative processes, stress, diabetes management, and distress. Two-hundred and fifty couples across the life span where one person has type 1 diabetes will complete a baseline interview, a 14-day daily diary, and a 6-month follow-up assessment. In Aim 1 we will identify the daily stressors experienced by individuals across the life span with type 1 diabetes that are linked to poorer diabetes management and distress. Couples will complete a web-based 14-day daily diary to assess daily stressors, diabetes adherence, mood, and blood glucose. Qualitative analysis of stressor content will reveal the general and diabetes stressors that interfere with daily diabetes management at different ages. In Aim 2 we examine the collaborative processes associated with better diabetes management and lower distress both daily and across six months and whether these processes are differentially important across the life span. Multiple collaborative processes are examined: appraisals that the illness is shared, collaborative coping when stressors arise, and video-recorded behavioral interactions when discussing a current diabetes problem. In Aim 3 we examine whether collaborative processes are especially beneficial for individuals with low executive function, using behavioral and self-report assessments of executive functioning. The proposed study takes an innovative multi-method approach to the social context of type 1 diabetes management over the life span, which has great potential for informing developmentally appropriate tailored interventions for adults with type 1 diabetes and their partners.